Sources and effects of contaminant exposure in seabirds

Anthropogenic contamination is ubiquitous throughout the marine environment. Understanding the sources and impacts of this contamination is important for our ability to mitigate pollution and prevent health effects in wildlife and humans. The goal of this research was to investigate sources and effects of contaminant exposure in wild seabirds. Specifically, these studies focused on assessing contaminant exposure sources and immune system effects in black-footed (Phoebastria nigripes) and Laysan (P. immutabilis ) albatross, large predatory North Pacific seabirds that forage over large oceanographic areas. First, new methods were established to assess immune function on cryopreserved avian peripheral white blood cells in order to evaluate contaminant-induced effects on immune function in wild albatross (Chapter 1). Contaminant levels and sources of exposure were evaluated in samples collected from black-footed and Laysan albatross in May–June of 2000 and 2001 on Sand Island, Midway Atoll (Chapters 2 and 3). Laysan albatross chicks on Sand Island, Midway Atoll continue to be exposed to substantially elevated levels of lead from the ingestion of lead-based paint at their nest sites, in spite of previous efforts to mitigate lead-based paint on the island (Chapter 2). Adult black-footed albatross had four-fold higher organochlorine (e.g., PCBs, DDTs) levels than adult Laysan albatross. These differences were best explained by their different foraging areas within the North Pacific. Furthermore, overall levels of organochlorine contamination may be increasing in the marine environment (Chapter 3). Black-footed albatross with high levels of contaminant exposure (e.g., PCBs, DDTs and mercury) had an altered in vitro immune response (increased lymphocyte proliferation and decreased macrophage phagocytosis) compared to birds with lower exposure (Chapter 4). Altered immune function can cause increased susceptibility to disease and infection, impacting reproductive success and survival. In conclusion, this research demonstrated that long-lived marine predators, black-footed and Laysan albatross, continue to be exposed to elevated levels of contamination, and that this contamination may be having detrimental health effects, possibly impacting their long-term survival.